But as successful as it's been, Rocket Internet has also received a lot of flak for its strategy to copy ideas that work in certain markets and build the same exact business model in regions that haven't yet been explored — earning such nicknames as "copycat," "clone factory," and "scam artist,” along the way.

But there's no question that Rocket Internet has built a massive business empire. Here are 15 of the biggest U.S. tech companies it "imitated" to get to where it is now.